Translator

Rocky and Dagster name things differently. Rocky has sources, tables, and models. Dagster has asset keys, groups, tags, and metadata. RockyDagsterTranslator decides how one becomes the other. Override a method to match your own naming conventions.

One method fills each part of the AssetSpec:

  Rocky input                             Dagster AssetSpec field
  ───────────────────────                 ───────────────────────
  source + table  ──get_asset_key──────►  key
  source          ──get_group_name─────►  group_name
  source + table  ──get_tags───────────►  tags
  source + table  ──get_metadata───────►  metadata

  ModelDetail     ──get_model_tags─────►  tags   (derived models)

Methods

get_asset_key(source, table) -> AssetKey

Returns the Dagster AssetKey for a given source and table combination.

Default: [source_type, *component_values, table_name]

get_group_name(source) -> str

Returns the Dagster group name for assets from a given source.

Default: first string-valued component (e.g., "acme"); list-valued components are skipped, and it falls back to source_type when no component value is a string

get_tags(source, table) -> dict[str, str]

Returns tags to attach to the asset.

Default: rocky/source_type plus one tag per string component (rocky/<component_name>)

get_model_tags(model) -> dict[str, str]

The derived-model counterpart to get_tags. It takes a ModelDetail instead of a source and a table.

It projects the model’s resolved [tags] onto the derived-model AssetSpec as Dagster tags. Resolved means the model’s own tags merged over any config group baseline. Once projected, a governance tag works in asset selection, for example tag:domain=finance.

Dagster’s tag charset is [A-Za-z0-9_.-], so Rocky sanitizes both keys and values against it. Every other character collapses to _, including whitespace, @, :, and /. Each key and each value is then truncated to 63 characters. A key that sanitizes to empty is dropped. An empty value is kept.

Rocky adds its own metadata tags on top: rocky/model_name, rocky/target_catalog, and rocky/target_schema. It adds rocky/strategy as well when the model declares a materialization strategy.

Those synthesized keys always contain a /. A sanitized governance key never can, because its / collapses to _. A governance tag therefore cannot overwrite Rocky’s metadata.

Default: the model’s sanitized [tags] plus rocky/model_name, rocky/target_catalog, rocky/target_schema, and (when present) rocky/strategy

For a model named customers materialized into analytics.marts.customers with the default full_refresh strategy and these resolved tags:

model.tags

{"domain": "finance", "owner": "data-eng@corp.com"}

get_model_tags(model) returns:

{
    "domain": "finance",
    "owner": "data-eng_corp.com",          # @ collapsed to _; the . and - survive
    "rocky/model_name": "customers",
    "rocky/target_catalog": "analytics",
    "rocky/target_schema": "marts",
    "rocky/strategy": "full_refresh",
}

get_metadata(source, table) -> dict[str, str]

Returns metadata to attach to the asset.

Default: source_id, source_type, plus last_sync_at / row_count when present, plus every adapter-namespaced source.metadata entry (e.g. fivetran.service) forwarded verbatim (non-string values JSON-encoded)

Custom translator example

from dagster_rocky import RockyDagsterTranslator, SourceInfo, TableInfo
import dagster as dg

class MyTranslator(RockyDagsterTranslator):
    def get_asset_key(self, source: SourceInfo, table: TableInfo) -> dg.AssetKey:
        tenant = source.components.get("tenant", "unknown")
        return dg.AssetKey(["bronze", str(tenant), table.name])

    def get_group_name(self, source: SourceInfo) -> str:
        return f"bronze_{source.source_type}"

Using a custom translator

Pass your translator instance to load_rocky_assets():

from dagster_rocky import RockyResource, load_rocky_assets

rocky = RockyResource(config_path="rocky.toml")
assets = load_rocky_assets(rocky, translator=MyTranslator())

defs = dg.Definitions(
    assets=assets,
    resources={"rocky": rocky},
)